This invention relates to a polyester having a narrow distribution of molecular weight and a process for producing the same, and a block copolymer of said polyester having a narrow molecular weight distribution and a process for producing the same.
Generally speaking, polyesters are produced by polycondensation reaction of a polybasic acid and a polyhydric alcohol. But since this reaction is a successive reaction, it was very difficult to produce the polymer having a narrow molecular weight distribution.
On the other hand, it is also possible to produce a polyester by ring-opening polymerization of an acid anhydride and an epoxide. But it was also very difficult to produce a polyester having a narrow molecular weight distribution.
Further, in condensation polymers such as polyester, it was very difficult to directly produce polymers having a narrow molecular weight distribution as mentioned above. In order to obtain a polymer having a molecular weight distribution in a narrow range, it had to use a process such as fractionation, and the like. In addition, in the case of condensation polymers, since condensation and decomposition take place at the same time, random copolymers are easily produced, while block copolymers are not obtained in general.